The enzyme project is centered around three problems dealing with conformational changes of the enzyme, elicited by specific nucleotides, stereochemistry of the substrate (2 types of catalytic activities) and symmetry. The enzyme under study is UDPGal 4-epimerase (from yeast or E. coli) can act like an aldose dehydrogenase (L-arabinose, D-galactose and D-glucose 2-deoxyglucose) provided 5' UMP is also present. ADPRibose (5/1) also falls into this category; in this case 5' UMP is not required. The other activity, the well-known UDPGal reversible yields UDPG epimerization is an oxido-reduction at the 4-position of the hexose transferring hydrogen to the bound NAD which is involved in both types of activity. The epimerase NAD (or NADH) is bound strongly into a protein dimer by hydrophobic forces. The symmetry, however, is aberrant: 1 NAD per 2 subunits instead of the usual prosthetic groups per 1 subunit. Another aberrant symmetry found in our laboratory is of the opposite type. A monomer protein with 2 binding sites for the same ligand (glucose or Beta-galactose or Beta-galactosides). This protein is a periplasmic sugar binding protein in E. coli. Addition of galactose (the Beta-anomer) changes the conformation of this protein as evidenced by charge tryptophan fluorescence and dissociation constant (decreased affinity; negative cooperativity?). The biochemical and genetic studies being carried out in our laboratory by Dr. Winfried Boos and in the biochemistry laboratory at the University of Wisconsin by Dr. Julius Adler, have indicated that this binding protein is involved in transport of galactose and Beta-galactosides as well as in chemotaxis towards glucose and galactose. Hence, cellular functions, including a primitive neurobiological function can perhaps be related rather directly with biochemical parameters. Studies of galactose transport and metabolism in mammalian cell cultures have shown an increase of the rate of uptake after transformation of hamster cell strains by polyoma virus. Replacement of glucose by galactose brings about a switch to an atypical aerobic metabolism which supports tumor growth very well and leads to a striking orientation of - the tumor cells. A study of correlation of oriented growth with the endogenous levels of cyclic AMP is under way.